Some viral and viroid diseases of plants

disease causative agent hosts symptoms and signs additional features

tobacco mosaic tobacco mosaic virus (TMV) tobacco, tomato, and hundreds of other vegetables and weeds mottled appearance of leaves (mosaic pattern); dwarfing virus remains viable for years in soil and tobacco; the disease occurs worldwide; significant economic losses can occur

cucumber mosaic cucumber mosaic virus (CMV) cucumber, bean, tobacco, and other plants (wide range of hosts) similar to those of TMV infections worldwide occurrence; very broad range of hosts

barley yellow dwarf barley yellow dwarf virus (BYDV) barley, oats, rye, wheat; also pasture grasses and weeds yellowing and dwarfing of leaves; stunting of plants one of the most important diseases of small grains

tomato spotted wilt tomato spotted wilt virus (TSWV) tomato, pepper, pineapple, peanut, and many other plants leaves show concentric, necrotic rings; necrotic region yellow, then turning red-brown very wide host range; infects hundreds of different plants

prunus necrotic ring spot prunus necrotic ring spot virus (PNRV) stone fruits—e.g., cherry, almond, peach, apricot, plum, and others delayed foliation; leaves on infected branches show light green spots and dark rings, then become necrotic and fall off very widespread disease of stone fruits; affects almost all trees in fruit-producing regions

potato spindle tuber potato spindle tuber viroid (PSTV) potato and tomato stunted growth; tubers are spindle-shaped and smaller than healthy tubers the first identified viroid infection in plants; can cause major reduction in crop yield

citrus exocortis citrus exocortis viroid (CEV) orange, lemon, lime, and other citrus plants infected trees show vertical splits in bark, thin strips of partially loosened bark, and a cracked, scaly appearance worldwide distribution; causes reduction of crop yield